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Need help with turbo issue

2K views 23 replies 3 participants last post by  The Dub Doc 
#1 · (Edited)
I bought the car used in 2017, Scirocco R (2013) 2.0 T FSI gasoline A/T, now at 66,000 km and supposedly APR Stage 2+ (but another garage told me it wasn't...don't know if this matters with my issue).

The turbo boost gauge is a Defi and reads in bar.

I noticed a few weeks ago while going up a small inclined stretch of the road a feeling of a bit of loss of power because I expected it to go up like it normally does with ease
but this time it wasn't and I quickly looked at the turbo gauge and the needle was like at 1 bar (15 psi) but I was only going maybe 60 km/hr and rpm was only at about 2000-2400.

Normally I just touch the pedal lightly and the car goes because it has a lot of power and torque so I'm used to not flooring it and pushing it hard just to get around. The turbo needle
almost never goes to 1 bar for me because I don't floor it and I don't need to race. Lately, even when I'm just accelerating gently from a stop / traffic light, the boost will read 0.5 - 1 bar
(10 - 15 psi) when I'm only pushing around 1800 - 2000 rpm and driving only 80 km/hr. I don't ever remember the needle go that high for such light driving. I'm not sure what is causing the
boost to go so high on such low speeds/rpm....it's more noticeable from a stop/traffic light as oppose to being at higher speeds.

No CEL despite still driving like this for weeks now. It drives for the most part fine, but I do feel like there's a loss of power (not as responsive or as much as I'm used to) especially from a stop and not as smooth when the needle goes up so high for just light driving.

I believe it may be a leak somewhere but I'm confused because if there was a leak, wouldn't it mean the pressure should be lower and not reading a lot of boost? My reading is showing the opposite, too much boost (or requesting too much boost) for such low speed.

This seems to only be when I am putting my foot on the gas. When I let it off, the needle reacts normally by going all the way back down to -0.8 bar or so, which I assume means no problem with the diverter valve (forge).

I think I will invest in the VCDS from rosstech they have for $199 and see if I can see live data on requested boost vs actual boost (something someone else advised to me).

Any other ideas what it might be? Should I take off my MAF sensor and drive around and see if drives better (maybe a dirty maf?), or could it be a bad N80 valve (if that might be related to this),
I already changed the charcoal canister. I also hear a hissing sound only when I accelerate at around 2000 or more rpms so I think it is a leak of some kind.

Another symptom I noticed was when I turn the AC on and sit at idle, the needle moves back and forth between -0.6 to -0.4 every second....it never used to sway back and forth like that even with AC on in the past. When I turn AC off, the needle calms down and sits steady at -0.7
 
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#2 ·
I could make some speculations based on the situational/observational info you have mentioned but it won't change the fact that the best, first thing you can do is what you already mentioned: get VCDS and log live data. I think I have a post in this section recently to someone else with more specifics on what exactly to log, how to go about logging (what kind of pulls to do), and interpreting the data but if you can't find it then let me know and I'll walk you through it when I get a chance. We need to see what the ECU is really reporting for your boost behavior not the gauge. There is some other data we'll want to have a look at too but we can start with the boost data.
 
#3 ·
Thanks I appreciate that! I have ordered the VCDS and it will take some time to ship to me. Once I get it, I'll install the software, try to learn the basics and run the live data log and then come back here and post the information!
 
#7 ·
Basic logic procedure is as follows:

1) Get car up to operating temp

2) Find a road with plenty of room, minimal or no traffic, and an easy way to turn around and get back on for subsequent logging runs (it will need to be safe to speed on)

3) Use "Advanced Measuring Values" so that you can log more than 3 values at once you start logging. Also make ABSOLUTELY sure you have "turbo" mode on before you start a log. It increases the sample rate of VCDS by about 10x which allows you do get data roughly every 40RPMs instead of every 400RPMs. This is absolutely crucial to accurate analysis. A lot happens in the space of 400RPMs that you don't want to miss.

4) Unless you are trying to log data to diagnose an issue that only happens in a certain running state like at idle or part throttle, otherwise a typical diagnostic log is best done at full load; therefore the typical log should be done from 2,000RPMs to at least 6,000RPMs at wide-open throttle (WOT). If logging for boost data do NOT roll onto the throttle, go WOT the second you start your pull. It is preferred to log in 4th gear but 3rd is fine too (hence what I mentioned in #2).

5) You should get a few different pulls logged so you have a greater sample size of data to pull from for analysis and can see trends emerge or control for flukes in the data of one log. These multiple pulls should be done on the same stretch of road, ideally, and should also not be done back to back because the car heat-soaks after the first pull. You want to give ample time for the car to cool down between pulls by driving at a good speed (for good airflow) but at low load/RPMs.

6) As for WHAT data to log, well, that's up to you based on what you're looking to diagnose. If you're just looking for general analysis then I typically log for engine speed (RPMs), accelerator pedal position, mass air flow, engine coolant temp, sum timing retard, lambda control bank 1 - specified, lambda control bank 1 - actual, fuel rail pressure - specified, fuel rail pressure - actual, boost - specified, boost - actual, and boost control - n75 duty cycle. The first 2 on those list should ALWAYS be in any log you ever do because when you output the log data to a .csv you need to be able to tell exactly where/when you were at full load and what RPM you were at. It is critical to data analysis. You can replace accelerator pedal position for throttle valve angle if you want to know the actual physical position of the throttle valve rather than the pedals input (but typically they should be equal - they wouldn't be only in a scenario where there's and issue with the signal from the pedal or the throttle body). The last 3 of the list are only for turbocharged cars, of course. With all these data points you can tell how much air the ECU is measuring coming in, how much boost the ECU is commanding and how it is controlling the boost vs. how much it is actually seeing the turbo make, how much fuel pressure it is commanding vs. how much it is seeing the HPFP make, reports from the 02 on how rich or lean you are running post-combustion of the aforementioned air and fuel amounts, the sum of timing retardation (if any), and generally how hot the engine is running. All of this is important data to consider to get a good sense of engine performance


Tip: when it comes to boost data you'll be getting it in millibar. Depending on where in the world you're from you may prefer it in bar or psi. If you prefer it in bar then, well, I'm sure I don't have to explain the conversion of millibar to bar for you. But if you prefer it in PSI because that is a reference point you're familiar with then you'll need to do some math. 1mbar is one-thousandth of 1bar; 1bar is 14.7psi and one-thousandth of 14.7psi is 0.0147. So we take a given mbar amount X 0.0147 to translate mbar to psi. But there's a little more to it than that. You also need to factor in the atmospheric pressure itself where you live. If you live at sea-level then the atmospheric pressure is 1013mbar. It varies a bit based on your elevation above or below sea-level so you'd have to look those numbers up and cross-reference them with the altitude where you live/logged the data. The reason for this is that your MAP sensor is reporting the total (or "absolute") pressure which includes the atmospheric pressure level where you live AND the additional pressure the turbo makes. You want to know ONLY how much boost pressure the turbo system is making which means you need to subtract the atmospheric pressure from the absolute pressure that the ECU is reporting in the log.

Example:

Log says the ECU is specifying 2300mbar. You (hypothetically) live near sea-level. Take 2300mbar (absolute pressure) and subtract 1013mbar (atmospheric pressure) = 1287mbar. Multiply 1287mbar by 0.0147 = 18.9PSI.

Around 2300mbar (about 19PSI near sea-level) is a typical boost number to see on a stage 1 tuned FSI (somewhat depending on the tuner). Not sure if you're tuned or not, but if you are stage 1 or stage 2 tuned you'll be looking for the ECU to specify numbers like that (give or take 100mbar) and you'll be looking for the turbo to meet that specification (represented by boost - actual) by around 3500RPMs for a K03 turbo. It will only meet for a bit and then it will taper off because the small K03 cannot hold that boost for long.
 
#15 ·
Even the P3Cars gauge can be inaccurate; the standard one doesn’t display exactly what it reads from the ECU like VCDS does. Rather, it interpolates the data somewhat and applies some calculations. It has different modes that change that math a bit based on how your car is setup (tuned or not tuned, etc.). These modes are called “Car.0”, “Car.1”, etc. They also offer a version of the gauge using “Vag blocks” which does display exactly what the ECU reads. I frankly don’t know why that isn’t the default version they ship. Anyway, the point is that the P3 gauge can be wrong too, especially if you didn’t explicitly order the Vag blocks version

I will concede, though, that the chances your mechanical boost gauge and digital boost gauge were both wrong and read exactly the same while being wrong are fairly slim. I’ll keep that in my mind for consideration as I see your data and try to interpret what is going on with your car.

That said, yes I am going to need that data to “agitate” the circumstances. It is still the best way I can measure how the car should be behaving vs. how it is behaving with a very clear distinction because, again, you operating the car whilst it is going through these issues is a lot different then me looking at numbers. Things must be more explicit for me in the numbers.

I will go over your existing data again more closely but I would still like the full-throttle data procedure, it won’t hurt anything as long as you maintain your vehicle decently, it can only help.

Yes it is a good idea to save any codes in the scan history, then clear codes, then also do a “capacity discharge”. You do this by taking the positive and negative leads for the battery and holding them or tying them together such that the metal of the end of each lead is in contact with the other. Do this so that are in continual contact for at least a few minutes. DO NOT bridge the battery terminals/posts! I am talking about the leads that fit over and clamp down on the terminals/posts. It is safe to touch the leads together, it is not safe to touch the terminals together.

Performing this capacity discharge will essentially reboot the ECU and cause it to forget the long-term fuel trim completely.

Starting from that clean slate is a very good idea.
 
#16 ·
thanks. Couldn't I just erase the long term trim codes from VCDS?
I've never tried what you suggested (about the battery leads thing) and I don't know that much about cars
to feel confident enough to attempt it without some assistance.

You've given lots of good information so it will take me time to understand and digest it. I will give it another
run on the weekend and try to get the data you are looking for (it would be good for me too I guess).

Would I be correct in assuming that if one had VCDS in the beginning, it would always be a good idea
to log readings when the car is running fine to keep a record of it and then one day if the car was having problems,
being able to compare the logs would show what is off in the readings?

I'm wishing now that I had logs of the car so that I could have compared the data and see what looks off but since I just
got the VCDS a few days ago, my first recorded logs are only in the current situation I'm in now.
 
#17 ·
thanks. Couldn't I just erase the long term trim codes from VCDS?
I've never tried what you suggested (about the battery leads thing) and I don't know that much about cars
to feel confident enough to attempt it without some assistance.
I have never found a straight answer about whether or not simply clearing codes erases ALL memory of long-term fuel trims. It may, but it may not. I have heard arguments from both sides and could see it either way. Ultimately it would come down to how memory is stored in the ECU and other matters of how the ECU software works that even myself as a software engineer and enthusiast are not privy to. One way that I know for absolute certain does, though, is the way that I described above. Maybe I made it sound scarier or more complicated than it is, but it is not. I thought to make a video for you to show since it would take about 30 seconds but then figured there would surely be one on the web already... sure enough there is and it's by our good friend the Humble Mechanic. Enjoy:

https://www.youtube.com/watch?v=vYtyDX9RTWs


Would I be correct in assuming that if one had VCDS in the beginning, it would always be a good idea
to log readings when the car is running fine to keep a record of it and then one day if the car was having problems,
being able to compare the logs would show what is off in the readings?
That would certainly be a good idea. Anyone who is fortunate enough to already have VCDS when they buy a brand new VW would be wise to do so. But technically speaking, that is about where the advantage ends because, technically speaking, if you are buying a used VW then unless you know basically everything about the vehicles operation and what the data should look like already then you don't know if your initial data collection is, indeed, a perfect template on which to compare any future data. Again, that's all "technically" speaking; but if you have sufficient knowledge about how the systems in the car operate and what data you should be seeing then, yes, you could get a good "template" data set on a used car. I've got plenty. But before you ask to see them so you can compare, it won't do you any good because my car is extremely modified so it won't do you any good to compare to mine. I don't think I have any thorough logs of my stock days anymore (that was years ago).

I'm wishing now that I had logs of the car so that I could have compared the data and see what looks off but since I just
got the VCDS a few days ago, my first recorded logs are only in the current situation I'm in now.
Don't fret about what you could/should done. And, I know I'm a broken record on this by now, but the kind of driving you do is just not conducive to logging that can be used effectively, EVEN IF that is all you do. I know that it is natural to think that because you never, ever push the car that this means you should be logging data that is also not pushing to car in the interest of logging consistently to what normal driving is like. Your head is in the right place from a "testing methodology" standpoint there, but there's an aspect of diagnosis through data that you're just not keen on because you are just learning and that aspect is basically what I explained earlier; you can only glean so much from data that is not at high load AND data that is inconsistent. You might think that your data under low load is consistent because you're consistently driving at low load, but that is a perfect example of where you're looking at the high-level and can't see the low-level; the low-level is that under your normal driving circumstances the numbers can say a lot of different things and since I'm not with you all I have to look at is the numbers and I can't see enough consistency. I have gleaned a couple things but I'm not committed enough to them to consider them significant. You just can't make an significant observations without high load data. Because at high load it you take all variability out of the equation: either something is working right or its not, no grey area, no room for misinterpretation (if you know what you're looking for). You can scope right in on the problem because it becomes plane as day when you agitate it with high load. Too much stuff can get covered up by low load scenarios.

But I'll leave it at that because I'm sure I've said enough... Let's just focus on what we CAN do now, which is do a cap discharge according to Humble Mechanic's instructions so that you can clear ALL ECU LTFT memory and then go do the logging I
 
#18 ·
I logged another run today and I pushed it harder than normal so I hope something shows up
in the data logs that may help you see anything out of the ordinary or unusual.

If the data is not sufficient and you are not able to determine anything unusual with the log,
then I will just leave the car as is until it gets noticeable worse, because it does seem to drive
fine other than the fact that the boost needle goes over 0 way more than it used to, even
under light load, easy driving, and low to mid range speed and rpm.

Here is the file i put on google drive:

https://drive.google.com/open?id=1f_C77cz2kajP2iEdibaBMLNvQzUREraK
 
#19 ·
This is semi-helpful. I can see the beginnings of what appears to be a healthy boost curve and control but I can't see the whole picture to confirm anything solid because you refuse to go above 3K RPMs with more than 50% throttle. The data is only going to confirm anything about the behaviors of your car beyond a shadow of a doubt if you do what I have told you to. I'm done explaining why at this point. I could go into even more detail, the extreme technical detail of why I NEED to see what I've asked for, but I'm not going to because it seems like it will be a waste of time. If you don't trust me when I say that absolutely nothing bad will happen if you follow my instructions to the letter then that's your choice, of course. In the end, you're only hurting yourself by choosing not to arm me with the info I need to help you to the fullest extent.

But if you aren't having an issue with drive-ability and you're happy with the car and just want to know what my opinion of the boost gauge readings are then know that your boost gauges (apparently both of them since you said they both read the same) are dead wrong. Your first post says that with very light throttle application to get started after a stop your boost gauge/s read up to 15 PSI... well, your data would say otherwise. Your data shows that you are only just reaching 15PSI when you're 50% throttle at around 3K RPMs with a wastegate duty cycle of about 50%. If you're only reaching 15PSI at that point (which sounds about normal) then you are sure as hell not anywhere near 15PSI in the situation you described in your first post. It's not even physically possible form a technical perspective, not the way this car is setup anyway. The boost control system would have to have failed woefully and be permanently closing the wastegate for that to even be remotely possible, if at all. But as I can see from the data, your boost control seems correct. I can't confirm 100% because you won't follow my instructions to allow me to see a FULL boost curve, but the half of it that I can see looks fine.

So I'll sum up my answer to your concerns in the original post base don what I know so far:


I noticed a few weeks ago while going up a small inclined stretch of the road a feeling of a bit of loss of power because I expected it to go up like it normally does with ease
but this time it wasn't and I quickly looked at the turbo gauge and the needle was like at 1 bar (15 psi) but I was only going maybe 60 km/hr and rpm was only at about 2000-2400.
Can't help with that, you haven't given me the data I need to address drive-ability/performance concerns...


Lately, even when I'm just accelerating gently from a stop / traffic light, the boost will read 0.5 - 1 bar
Boost gauge is definitely not accurate; you're only hitting 15 PSI with 50% load and higher RPMs (higher then when you're starting from a stop). You'll be nowhere near 10-15PSI when just gently starting from a stop.


When I let it off, the needle reacts normally by going all the way back down to -0.8 bar
This is accurate. You should be around -0.8bar / -23H/g at idle.


Another symptom I noticed was when I turn the AC on and sit at idle, the needle moves back and forth between -0.6 to -0.4 every second....it never used to sway back and forth like that even with AC on in the past. When I turn AC off, the needle calms down and sits steady at -0.7
This sounds like normal behavior. When you turn on the AC, which is obviously belt-driven by the ENGINE, you are adding load to the engine which will slightly change RPMS and engine load of course, which will impact the amount of vacuum slightly and it will be a little less steady then when the AC is off. So seeing a slight change in the vacuum reading on a gauge when the AC goes on or off is normal. It is actually NOT normal if you previously never saw that so I suspect maybe you just thought it never did that before and only noticed that behavior now because you thought you had an issue and are being extra vigilant.
 
#21 ·
Oh, I forgot to mention something. The reason why the turbo needle was moving massively back and forth between -0.4 to -0.2 when stopped at a red light with AC on was because later at the shop, I found out I didn't fasten my engine oil dipstick completely. It was essentially a leak and I was probably driving around like that for a few weeks (with the dipstick not fully sealed). That probably explains why I was having those weird fluctuating sounds from the engine when resting at a redlight. Once they re-fastened the dipstick completely, I thought maybe my turbo issue would be resolved but that part was still the same (turbo working harder than it should is what it seems to me, even at low speeds) and light throttle/acc pedal.
 
#22 ·
I do agree that how I explained it in the beginning may not be accurate because trying to explain it and experiencing the drive is difficult to put into words. I will agree it wasn't at 15 PSI from light acceleration from stop but it seemed to me very unusual and something I never saw or noticed in the 2 years I've own this car. I would be cruising at 40 or 60 km/h and step on it a bit to get to 100 km/h and sometimes I noticed it would go over 1 bar, even in the last run I did, I noticed one time it was between 1 to 1.5 bar and I've never recalled seeing the needle go that high for not even flooring it WOT.
Okay, regardless of how you explained it, the gist of it was that starting out gently form a stop you saw some noteworthy amount of boost straight away... that's not how it works. You have next to zero boost in that scenario. And you sure as hell don't have up to 1.5bar just from "stepping on it a little bit"... 1.5bar is the absolute max boost you can get out of APR stage 2+ tune and you will only ever see that much boost if you are flat out WOT. Bottom line is: your boost gauge/s are wrong.


To be honest with you, I'm just way too scared to even try WOT on the public roads. My previous fastest car I've ever owned was a 130 hp ford focus (I've driven that 160 km/h a few times on the highway, but full acceleration, there's not that much power to be afraid of). Now driving in a 265 - 300 hp car is a day and night difference for me and I'm sure for the experienced guys out there who have raced, gone on tracks, and driven cars with over 500+ hp, this is nothing to them. But for me, hitting 4000 or 4500 rpm is like driving life my life depended on it because the car just goes so fast and pulls so hard that I'm hitting 160-180 km/h in no time and the car is really loud and shakes and I feel like it's going to blow up or something if I push it more.
If you find an open road with limited-to-no traffic and visibility at distance on both sides of the road (as opposed to wooded sides) basically nothing can go wrong and that would be a good place to get comfortable with pushing the car faster and harder. It would also be the ideal place for proper data logging per my instructions. Just food for thought.

Now, if you say that taking your car to 160kph causes it to start shaking and getting loud then you have some kind of problem. 160kph is nothing to these cars. It should be as smooth at 160kph as at 80kph. Sounds like a problem. My car is smooth at 260kph and I have an enormous amount of stiffening modifications that increase noise, vibrations, and harshness, as well as a turbo that is pushing my engine to the ragged edge. Even every limit that exists my car does not shake. Yours shouldn't either. Speed-related shakes are not necessarily an engine problem either, you might need a tire mount and balance, you might need a good suspension alignment, or you might have a bent wheel... any number of other of things.


In the past when I first got the car, I did drive it hard a few times (again hard for me is like 4500 rpm) and I remember I went into limp mode in two separate occasions. At the time, I didn't know what LIMP MODE was. I had never heard about it, I had never experienced it. So the first time was when I was driving a bit hard doing 140 km/h in a 80 zone just racing past everyone and then suddenly the engine sputtered and lost power and I was reduced to a slow crawl. I thought to myself, "Oh f$*%! Did I blow the engine?" I seriously thought I killed the engine for driving hard.

I understand your fright in that situation considering you didn't know what the hell happened and what limp mode is at the time but this actually goes to my point in one of my earlier posts... the ECU and the plethora of sensor suites on this care will literally not let you hurt the engine. Trust me when I say that there is a sensor to pick of literally any kind of abnormality. It is almost impossible to hurt your engine unless you just blatantly neglect it (like letting it run really low on oil and stuff like that). These engines are extraordinarily robust. I am making over double the factory HP and TQ (substantially more than your stage 2+ tune) on my stock FSI motor and pushing it to the absolutely limits at the race track where coolant and oil temperatures sore far higher than you will ever see on the street even if you go absolutely as hard as you can; even the most aggressive street driving does not hold a candle to the abuse at the race track. My engine is still going strong. It will have a much shorter run than yours, but that's fine. My point is, you're not close to pushing the limits of your engine from a power-standpoint AND if any other conditions were to arise that would be dangerous to it the ECU will know and limp mode is there to protect you. You basically can't hurt it unless you physically sabotage it or neglect it.


This time I got a fault code and it was just a loose connector (EPC light) fault code p2294. The shop just cleaned it up and fixed the connector for me again and no problems after that. I've driven it 180 km/h and it never went into limp mode again.
Classic throttle position sensor on the throttle body.


The car seemed to drive normal, I didn't notice anything wrong but I don't know if it was coincidence of it's related, but that's around the time I first noticed the difference in my boost reading and feeling of loss of power simply going up a small hill. I think it was only 1 or 2 weeks apart at most (from the day of that emissions testing to the first day I noticed something weird about feeling of loss of power and why the boost gauge was reading so high for just going up a tiny hill that I normally had no problems conquering with just 2k rpm but that specific moment I remember pushing the pedal like I normally do, but this time the car didn't seem to conquer that hill, and I pushed the pedal down even more than I usually do to go over that tiny hill and that's when I noticed an unusual feeling of lack of power yet the boost needle well into the + and it wasn't going like it should or normally does.
What that guy did was absolutely ridiculous and you should have chewed him out and then reported his ass to his manager because that's blatant disrespect for another person's property. It may have increased some wear of metal components in the engine because the oil was not at operating temp and viscosity but in the grand scheme of engine wear over the life of a vehicle it would have been fairly insignificant and it did not damage your car nor did it cause your boost concerns. There are no systems related to the engines boost control that would have been impacted by that incident. Diagnostically speaking, these are separate concerns. Again, all evidence suggests that your "boost issue" is not an issue but rather incorrect gauge readings. Until I see better data, that's what I'm sticking to. The only way the guy could have hurt your car is if he actually wore out an engine internal that requires lubrication all at once and it has compromised compression in the engine. If it was a fairly brief red-line under a few seconds then I find the likelihood of that exceedingly low. The white smoke was condensation in the exhaust and oil burning off since the car hadn't made it up to temp yet. It wasn't your engine getting hurt.

As far as I'm concerned, the guy was an ******* but he didn't hurt your car. If you want to provide yourself the means to stop fixating and put your mind at ease then you need to do 2 things:

1) Get a compression test performed
2) Give me the data I am asking for

If you do those 2 things you will have an answer as to whether your engine and turbocharging system are operating properly. And if they get the all clear then we can move on to other causes of power loss. There could be something else going on and it could have been festering for some time, long before the guy revved your cold engine, because you've already stated that your car shakes at over 160kph and, again, that's not normal. While it could be something totally unrelated to engine performance (like suspension/wheels/tires) it could also be related.


At this point, I'm going to leave it as is but I know for sure I'm not imagining or making any of it up. I know the difference. I felt the difference. It's like I could do it blindly with my eyes closed and just based on the feeling, I know how the car was supposed to respond and know that something happened starting that day.

I believe you that your car is making less power than it should, I will trust your attunement to your car, but as far as I can see it isn't a boost issue and I highly doubt it's an engine issue or you'd have much worse problems. You can either choose to go with that or you can do the 2 things I mentioned above and provide new data/evidence to suggest otherwise so we can make further progress. It sounds like your mind isn't going to be at ease until you put them to rest, so why not just take my advice so you can see this through instead of settling for "I know something is wrong but the car drives okay so I guess I'll just have to deal with it". That's just not rational. Let me also put it to you this way: you've said that you intend to keep VCDS and save yourself time and money by trying to diagnose things yourself when they come up rather than going to the dealership that is 3 hours away... well let me just tell you that the very first time you start to have a real serious problem like a fueling issue or a boost leak or something like that, you're going to need to follow the logging procedures I have laid out because that's how it's done. You're gonna have to do it some day so may as well get comfortable with it now.

If you still don't want to then we will agree to disagree the practicality of your decision, I'll respect your decision as the owner of your vehicle, and I'll leave it at that.
 
#23 ·
Okay, regardless of how you explained it, the gist of it was that starting out gently form a stop you saw some noteworthy amount of boost straight away... that's not how it works. You have next to zero boost in that scenario. And you sure as hell don't have up to 1.5bar just from "stepping on it a little bit"... 1.5bar is the absolute max boost you can get out of APR stage 2+ tune and you will only ever see that much boost if you are flat out WOT. Bottom line is: your boost gauge/s are wrong.




If you find an open road with limited-to-no traffic and visibility at distance on both sides of the road (as opposed to wooded sides) basically nothing can go wrong and that would be a good place to get comfortable with pushing the car faster and harder. It would also be the ideal place for proper data logging per my instructions. Just food for thought.

Now, if you say that taking your car to 160kph causes it to start shaking and getting loud then you have some kind of problem. 160kph is nothing to these cars. It should be as smooth at 160kph as at 80kph. Sounds like a problem. My car is smooth at 260kph and I have an enormous amount of stiffening modifications that increase noise, vibrations, and harshness, as well as a turbo that is pushing my engine to the ragged edge. Even every limit that exists my car does not shake. Yours shouldn't either. Speed-related shakes are not necessarily an engine problem either, you might need a tire mount and balance, you might need a good suspension alignment, or you might have a bent wheel... any number of other of things.





I understand your fright in that situation considering you didn't know what the hell happened and what limp mode is at the time but this actually goes to my point in one of my earlier posts... the ECU and the plethora of sensor suites on this care will literally not let you hurt the engine. Trust me when I say that there is a sensor to pick of literally any kind of abnormality. It is almost impossible to hurt your engine unless you just blatantly neglect it (like letting it run really low on oil and stuff like that). These engines are extraordinarily robust. I am making over double the factory HP and TQ (substantially more than your stage 2+ tune) on my stock FSI motor and pushing it to the absolutely limits at the race track where coolant and oil temperatures sore far higher than you will ever see on the street even if you go absolutely as hard as you can; even the most aggressive street driving does not hold a candle to the abuse at the race track. My engine is still going strong. It will have a much shorter run than yours, but that's fine. My point is, you're not close to pushing the limits of your engine from a power-standpoint AND if any other conditions were to arise that would be dangerous to it the ECU will know and limp mode is there to protect you. You basically can't hurt it unless you physically sabotage it or neglect it.




Classic throttle position sensor on the throttle body.




What that guy did was absolutely ridiculous and you should have chewed him out and then reported his ass to his manager because that's blatant disrespect for another person's property. It may have increased some wear of metal components in the engine because the oil was not at operating temp and viscosity but in the grand scheme of engine wear over the life of a vehicle it would have been fairly insignificant and it did not damage your car nor did it cause your boost concerns. There are no systems related to the engines boost control that would have been impacted by that incident. Diagnostically speaking, these are separate concerns. Again, all evidence suggests that your "boost issue" is not an issue but rather incorrect gauge readings. Until I see better data, that's what I'm sticking to. The only way the guy could have hurt your car is if he actually wore out an engine internal that requires lubrication all at once and it has compromised compression in the engine. If it was a fairly brief red-line under a few seconds then I find the likelihood of that exceedingly low. The white smoke was condensation in the exhaust and oil burning off since the car hadn't made it up to temp yet. It wasn't your engine getting hurt.

As far as I'm concerned, the guy was an ******* but he didn't hurt your car. If you want to provide yourself the means to stop fixating and put your mind at ease then you need to do 2 things:

1) Get a compression test performed
2) Give me the data I am asking for

If you do those 2 things you will have an answer as to whether your engine and turbocharging system are operating properly. And if they get the all clear then we can move on to other causes of power loss. There could be something else going on and it could have been festering for some time, long before the guy revved your cold engine, because you've already stated that your car shakes at over 160kph and, again, that's not normal. While it could be something totally unrelated to engine performance (like suspension/wheels/tires) it could also be related.





I believe you that your car is making less power than it should, I will trust your attunement to your car, but as far as I can see it isn't a boost issue and I highly doubt it's an engine issue or you'd have much worse problems. You can either choose to go with that or you can do the 2 things I mentioned above and provide new data/evidence to suggest otherwise so we can make further progress. It sounds like your mind isn't going to be at ease until you put them to rest, so why not just take my advice so you can see this through instead of settling for "I know something is wrong but the car drives okay so I guess I'll just have to deal with it". That's just not rational. Let me also put it to you this way: you've said that you intend to keep VCDS and save yourself time and money by trying to diagnose things yourself when they come up rather than going to the dealership that is 3 hours away... well let me just tell you that the very first time you start to have a real serious problem like a fueling issue or a boost leak or something like that, you're going to need to follow the logging procedures I have laid out because that's how it's done. You're gonna have to do it some day so may as well get comfortable with it now.

If you still don't want to then we will agree to disagree the practicality of your decision, I'll respect your decision as the owner of your vehicle, and I'll leave it at that.

I agree with practically everything you said. I know that since I don't fully understand cars, how they work, and the capabilities of the parts, what I would think as being "hard" on the car is more like still babying it. I always wished there could be some sort of mandatory extreme emergency driving course where people could test drive a car to the upper limits and extremes just to get the feel and experience of what that is. Then when they are driving their own cars in normal conditions, we would know that we driving well within safety limits of the car's abilities. It's like someone who hasn't pushed the limits would never know how far and much more you could go and think that what they are currently at or doing is the upper limit (when it is not).

I am fully aware of what "ignorance" and "fear" does to people including myself. Simply not knowing or understanding whatever it is (a car, people/culture, technology/machinery etc) we have all sorts of invalid fears and assumptions and one day would look back and think "I can't believe I used to think this was scary or this was hard". That's why you sharing your experiences and feedback is very helpful and I can see where you are coming from (the side where you have seen it all or done it all and seeing someone like me on the other side being all unsure and fearful because of simply not knowing).

I'm glad you think it's not a boost or an engine issue. How or where can I do a compression test? Would you recommend me trying the DIY leak tests that are all over youtube? Apparently you just spray soapy water onto all the tubing, valves, connectors, and see if any bubbles starting coming up and you'd find a leak. I've also heard about some sort of fluid you can put into the system and if it leaks anywhere, you'd see it easily with blacklight. Would you recommend it?

If VCDS is not showing fault codes, then can I assume everything is ok for now and not worry too much about it? While I'm still positive something did change since that time, the car drives fine...it's not like there's any major issues with driveability...just that I'm sure I am noticing a loss of power at times when the boost is being asked to go so high when I'm not even driving it hard. But as you said, there are sensors everywhere and the technology on these cars won't allow us to damage our cars (unless we neglect it). Then since there is no fault code, maybe I should just leave it for now? That's why I invested in VCDS to at least give me the information if there was a code or no codes.
 
#24 · (Edited)
I respect that you see where I’m coming from and I see where you from even if I disagree, so we have a mutual understanding and you’ve explained that all well.

As far as I am concerned you don’t have a boost leak or boost issue. If you did you sure as hell wouldn’t be making 15PSI (just over 1bar) at 3K RPMs at 50% throttle and with an only half-shut wastegate, all according to the data from the ECU which is accurate. So I think you can forget about the boost like test. But just for the record, if you were to do one I would suggest the bubble test; do not put fluids/dies in your charge system ever.

The compression test can be done DIY pretty easily and it would be much easier for you to google/YouTube it than for me to explain it, as far as the procedure goes. But I will tell you what you are looking to find from it. The absolute most ideal compression result would be 180PSI (12.2bar) on ALL 4 cylinders. Realistically you won’t see that, that is what it’s be like off the factory floor. But you should have see numbers close to that. Anywhere in the 170s is great. Even the 160s is fine. 150s is okay but not particularly ideal, and anything less then that is bad. But what is most important is uniformity. All cylinders should be within about 5PSI (.33bar) of each other. If there is more variance than that on a particular cylinder then we can start be suspicious of the condition of the compression rings for that cylinder or perhaps the piston/cylinder wall themselves, especially if it varies by like 10PSI (.66bar) or more from the others.

Generally speaking, if you do not have a trouble code stored in the ECU, be a “hardcode” which would be stored as a CEL or be it a “soft code“ which would not be stored as a CEL, either way you can fairly reasonably assume that there is no serious or even moderate problem. The ECU will throw a code for nearly any issue related to boost, throttle position, airflow, fueling, timing issues, ignition issues, engine issues that are severe enough to cause misfires or engine knock/pre-detonation, and a handful of other things but those cover the major ones. That leaves very little that can go wrong and not throw some sort of code.

At some point it would be worth circling back and investigating the matter of your fuel trims, as I recall that they were pretty irregular and even though I could think of some explanations for why given the way that you drive your car, it is possible that there is something else to that. I believe where we left off with that was that I gave you some steps to follow that involved clearing the ECUs memory for fuel trims and then re-logging for both short-term and long-term trim data. Did you get around to that?
 
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